Strong and weak acids and bases

Answer Key - Grade 10 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   Acetic acid at 0.1 M has [H⁺] = 0.0013 M. What percent of its molecules have ionized, Ari?

   1.3 %
2. 2.

   Acetic acid at 0.5 M has [H⁺] = 0.003 M. What percent of its molecules have ionized, Bo?

   0.6 %
3. 3.

   Acetic acid at 0.01 M has [H⁺] = 0.00042 M. What percent of its molecules have ionized, Esme?

   4.2 %
4. 4.

   Which phrase describes a dilute acid rather than a weak one, Jun?

   • Little acid per liter of water
   • A pH that is above 7
   • Few molecules split into ions
5. 5.

   Can a solution of a strong acid be dilute, Kira?

   • No: a strong acid can't be dilute
   • No: dilute means weak
   • Yes: strength and amount differ
6. 6.

   Which has more H⁺: 0.10 M HCl or 0.10 M acetic acid, Luz?

   • The acetic acid
   • They are equal
   • The HCl
7. 7.

   Ammonia, NH₃, is a weak base. What does that mean, Milo?

   • Few NH₃ molecules take a proton
   • It has no hydrogen atoms
   • Each NH₃ takes a proton
8. 8.

   Ammonia has Kb = 1.8 × 10⁻⁵. Is it a strong or weak base, Pia?

   • Weak: its Kb is small
   • Strong: its Kb is small
   • Strong: it smells sharp
9. 9.

   What does a larger Ka tell you about an acid, Ren?

   • It is a stronger acid
   • It is a weaker acid
   • It is a more dilute acid
10. 10.

    Acetic acid has Ka = 1.8 × 10⁻⁵. What does the small Ka show, Zee?

    • It has no hydrogen to give
    • Most molecules stay whole
    • The vinegar is very dilute